I am trying to file the simple CA-1040 form. My only income is social security. You say, some CA forms are not ready. Is the CA-100 ready?

The California tax return is form 540.  State Forms Availability for individual tax returns

https://ttlc.intuit.com/community/forms/help/state-forms-availability-table-for-turbotax-individual-personal-tax-products/00/26227

Looks like the CA 540 return won't be ready until Jan 28.  Are you doing a corporation return?  The 100 is a Corporate return.